Thread: Do diamonds wear

Originally Posted by prodigy

If you think it's the diamonds getting "worn" I'd like to understand how and why with evidence. Diamonds are the hardest material known to man and I really don't think rubbing them on a stone is wearing them one bit. Now the steel plate holding the diamonds might be wearing out, and losing its hold on the diamonds, but the diamonds themselves are not being "worn".

To put it bluntly, you are wrong. Diamond is the hardest natural substance we know of. This doesn't make it invincible. Everything wears, including diamond. The wear mechanism differs, from small fractures to flattening and rounding off of the diamond abrasive particles. Any machinist who uses diamond points to dress grinding wheels (mostly aluminum oxide, the same abrasive used in most synthetic hones) can give you firsthand knowledge of that fact, which is why it's standard practice to rotate a diamond dresser with every few uses to prevent a flat forming.

It happens faster with powered grinding wheels, sure, but it happens with hand lapping very hard stones just the same. For instance, my Atoma 400 will flatten my SG20k if it's not very far out of flat, but it takes quite a while and quite a bit of pressure as well. When the Atoma was new it would rip that hone down in a minute flat. Using it to lap very hard natural stones like Arks & c. dulled it down pretty quick. It will still cut steel pretty fast, but hard hones not so much.

Hear hear!

Originally Posted by eKretz

To put it bluntly, you are wrong. Diamond is the hardest natural substance we know of. This doesn't make it invincible. Everything wears, including diamond. The wear mechanism differs, from small fractures to flattening and rounding off of the diamond abrasive particles. Any machinist who uses diamond points to dress grinding wheels (mostly aluminum oxide, the same abrasive used in most synthetic hones) can give you firsthand knowledge of that fact, which is why it's standard practice to rotate a diamond dresser with every few uses to prevent a flat forming.

It happens faster with powered grinding wheels, sure, but it happens with hand lapping very hard stones just the same. For instance, my Atoma 400 will flatten my SG20k if it's not very far out of flat, but it takes quite a while and quite a bit of pressure as well. When the Atoma was new it would rip that hone down in a minute flat. Using it to lap very hard natural stones like Arks & c. dulled it down pretty quick. It will still cut steel pretty fast, but hard hones not so much.

Everything you said defies geology and physics. I still think it's the diamonds losing hold of the plate that's the issue. Less diamonds, less cutting power. If I'm wrong, then everything I've learned in geology and physics must be wrong too?

Yup. This is why diamond cut-off wheels use sintered diamond matrix segments. As the diamonds wear and fracture, they are pulled out or fall out and are replaced by the next diamonds underneath as the matrix is subsequently worn away. None of this "defies geology and physics" - although a substance that never wears or breaks down certainly would! Diamond plates are a little different in that the diamonds are not designed to fall out and be replaced - so they are bonded using a stronger method - though some still pull out of the bond.

BTW, Google is your friend. Here's a link to a list of references if you're really interested in learning about this:

https://books.google.com/books?id=PU...20wear&f=false

I'm not really trying to argue. I am interested in this stuff. I think you guys mean to say something else, and we are in confusion. Diamonds, like everything else, do wear, I'm not denying that aspect. I have looked through many articles, and everything I've found so far supports my thoughts.

High speed grinders in an industrial setting, might be causing fractures. However we arent talking about industrial applications. The diamond plates used for flattening, simply just do not wear and erode the actual diamonds. Just like in nature, everything around the diamonds wears away. You can't scratch glass with copper. It doesn't matter how hard you try, how long you try, it won't happen. The diamonds likely aren't fracturing in the application of flattening stones, at least not after its been broken in.

I'm by no means an expert and I am actively looking this stuff up. Please continue to show sources that support your claim.

Diamonds come loose off the plates, as well as micro chipping (they are hard but also brittle) will round the sharp corners until they do not cut very effectively any more.

I lapped my Suehiro with my new Atoma 400, it worked very fast. Now after months of use of the Atoma I notice it is slower on the Suehiro.

Originally Posted by mainaman

Diamonds come loose off the plates, as well as micro chipping (they are hard but also brittle) will round the sharp corners until they do not cut very effectively any more.

I lapped my Suehiro with my new Atoma 400, it worked very fast. Now after months of use of the Atoma I notice it is slower on the Suehiro.

Right. But they aren't being "eroded" in the sense of river rocks being eroded by water, right? They are either fracturing into smaller pieces or being removed from the plate due to the weakest link being the binder that holds them to the steel?

Originally Posted by prodigy

Right. But they aren't being "eroded" in the sense of river rocks being eroded by water, right? They are either fracturing into smaller pieces or being removed from the plate due to the weakest link being the binder that holds them to the steel?

I think it is more like chipping off on the sharp edges until they get too rounded to cut aggressively.

Before I retired I used to hone razors at the tattoo shop when I had down time. I had a Norton 4/8 combo and a DMT 1200 at the shop. I had just started doing this and noticed that when I flattened the white 4k side of the combo stone I was getting a grey residue on the white hone. Fortunately for me, right about that time hi_bud_gl posted this thread http://straightrazorpalace.com/hones...w-problem.html

I took the 1200 home and checked it out with a 40x B&L stereoscope, and I hadn't peeled the bonded diamonds off of it. Only ......... I assume ...... worn the surface a bit. The plate still cut if i wanted to set a bevel or whatever. I don't know how many times I've seen someone on the forums refer to a 'worn' diamond plate. Of course whether the diamonds are actually wearing down, or they are stripping off of the substrat that bonds them i couldn't say for sure.

One way or the other, my DMT 325 and my Shapton glass DLGP do not cut as efficiently as they once did, though they still work. I bought the DMT XX 120 plate at the recommendation of Utopian and ChrisL. They were flattening barber hones with that animal and highly recommended it. Matter of fact, IIRC the 'new' DMT reference lapping plate is the same grit. Chris and Ron later lamented the fact that the XX wasn't cutting as effectively as it once did, they assumed the tough barber hones had worn down the diamonds slowing it down.

Shortly after hi_bud_gl posted the aforementioned thread Dia-Sharp (DMT) added to their FAQ. They said that no plate should be used to flatten waterstones above 325 grit. Any plate used to flatten waterstones should only be used under running water. So it would seem that diamonds can indeed wear.

Right on fellas. They do wear, whatever the actual mechanism - if you read some of the cited works I posted a link to earlier there are several that cover this very subject. They wear due to fracturing, chipping and abrasion. Even just the corners rounding off is enough to cause significantly more pressure to be necessary to do the same work. This happens pretty quickly with powered equipment and slower with manual equipment like our beloved diamond plates, but it still happens nonetheless.